1. Field of the Invention
The present invention relates to a method for producing an ink jet head.
2. Description of Related Art
Communication devices such as a facsimile apparatus or information processors such as a personal computer generally have a recording device capable of recording data including characters and figures on a printing sheet to record the data as visual information. For such the recording device, various types of printing methods such as an impact type, a thermal type, and an ink-jet type are used. In recent years, an ink jet recording apparatus using an ink jet type recording which is superior in silence and enables printing on a printing sheet made of various materials has received attention.
The ink jet apparatus is provided with an ink jet head for printing data such as characters and figures by ejecting ink onto a printing sheet. The ink jet head is, as shown in FIG. 15, provided with an actuator board 72 which is made of an piezoelectric element. On the actuator board 72, a plurality of piezoelectric side walls 73 and concave grooves 74 are alternately arranged. Each of the piezoelectric side walls 73 is constructed of a piezoelectric layer which is polarized in a height direction of the side wall 73, each surface of the piezoelectric side walls is provided thereon which an electrode 75. The electrode 75 is provided on each surface of the piezoelectric side walls 73 so as to be independent of each other. The electrodes 75 are connected conductably with conductive patterns 87 which are formed of conductive layers provided on closing portions 74A for closing back ends of the concave grooves 74 respectively. To the conductive patterns 87, a plurality of lead wires 85 are connected by a soldering way and the like. Each of the lead wires 85 is also connected to a printed lead wire 86A provided on a print board 86 by, for example, a soldering operation to connect each electrode 75 to a control unit 88 of the recording apparatus.
A cover plate 80 provided with an ink supply port 79 is adhered on a grooved side of the actuator board 72. This cover plate 80 and each of the concave grooves 74 construct an ejection channel 81 in which ink is to be supplied. A nozzle plate 82 for closing each ink chamber 81 is adhered to an end of the actuator 72 and the cover plate 80. In the nozzle plate 82 are formed a plurality of nozzles 83 individually corresponding to the ejection channels 81. It is noted that the ejection channel 81 is connected with an ink storing tank not shown through the ink supply port 79.
The ink jet head constructed as above is produced by the following producing method.
First, the actuator board 72 is subjected to a grooving process plural times to make grooves each of which opens at one end of the actuator board 72 in a longitudinal direction thereof (the direction A in FIG. 15) and extends close to another end, whereby a plurality of concave grooves 74 and the piezoelectric side walls 73 are formed so as to be arranged alternately in a width direction (the direction B in FIG. 15) of the board 72, both which extend in the longitudinal direction parallel to each other.
Next, a conductive layer of metallic thin film is formed by a vacuum deposition method on each upper surface and both side surfaces of the piezoelectric side walls 73 and each upper surface of the closing porion 74A. Thereafter, the upper surfaces of the piezoelectric side walls 73 are subjected to a grinding process to remove the conductive layer therefrom, thereby to form the independent electrode 75 on each side surface of the piezoelectric side wall 73. After that, while each lead wire 85 is welded to the conductive patter 87 of the closing portion 74A corresponding thereto by a soldering operation and the like, the cover plate 80 and the nozzle plate 82 are adhered to the actuator board 72, which completes the manufacture of the ink jet head 71 provided with a plurality of ejection channels 81 in which ink is supplied.
The ink jet head 71 produced as above is installed in the recording apparatus and connected to the ink storing tank through the ink supply port 79 of the cover plate 80, thereby filling each of the ejection channels 81 with ink. Prior to the installation of the ink jet head 7 in the recording apparatus, each of the lead wires 85 is welded to each of the lead wires 86A of the printed board 86 by a soldering operation and the like to connect the electrodes 75 to the control unit 88 respectively. In the ink jet head 71, a predetermined ejection channel 81 is selected according to data including characters or figures, and driving voltage is applied to the electrodes 75 of the adjacent piezoelectric side walls 73 through the corresponding conductive patterns 87 thereby to deform the piezoelectric side walls 73 to reduce the volume of the ejection channel 81. The ink jet head 71 then ejects ink through the ejection channels 81 by an ejection energy resulting from the positive pressure in the inside of the ejection channel 81.
However, in the ink jet head producing method in the prior art, a plurality of lead wires 85 are needed to be welded by a soldering operation at two points, i.e., the conductive pattern 87 and the lead wire 86A of the printed board 86, to connect each electrode 75 provided on each side surface of the piezoelectric side wall 73 with the control unit 88 of the recording apparatus. This may cause a complicated operation to connect the electrode 75, and an increase of soldered portions may causes many inconveniences such as connection failure or cross-connection, resulting in a deterioration in the reliability of connection and the reliability of ink ejection.